When the sun rose on April 19, 1993, it marked the 51st day of a standoff between dozens of federal agents and members of an apocalyptic religious sect called the Branch Davidians, who had barricaded themselves in their compound outside Waco, Texas.
"Nothing about April 19th started normal, nothing," said Waco survivor and former Branch Davidian member David Thibodeau. "It was windy."
The winds were as high as 30 to 35 miles per hour that morning, said FBI agent Jeff Allovio, so strong that it was hard to hear anything outside of his vehicle.
Mary Garofalo, a journalist who covered the events at Waco for the news program, "A Current Affair," said she thought it was just going to be like any other day in the past weeks of the standoff.
"Except this time, when I looked through the binoculars. I saw a tank with an extended arm," she said. "Then we realized they were going in."
Watch "Truth and Lies: Waco," the documentary event, on Thursday, Jan. 4 at 9 p.m. ET on ABC
The siege began on Feb. 28, 1993, when 76 agents from the Bureau of Alcohol, Tobacco and Firearms arrived at the Mount Carmel Center compound with a search warrant to look for illegal weapons. A shootout between federal agents and Branch Davidians ensued, killing four ATF agents and six Davidians.
"Everyone thinks that we're monsters, that we attacked innocent people," said ATF agent Robert Elder. "We didn't drive up there and start shooting and killing people. We responded with deadly force because deadly force was used against us."
It led to a 51-day standoff with FBI negotiators making several attempts to reach a peaceful outcome with the sect's leader David Koresh, especially for the release of the 46 children inside the compound.
The Branch Davidians had stockpiled food, water, firearms and gas masks for weeks. Within the first five days, 21 children were released and taken to Methodist Children's Home in Waco.
Psychiatrist Bruce Perry, who volunteered to help counsel the children, told ABC News that it was immediately clear that the children were afraid. He said their resting heart rates were twice as high as expected for a normal child.
"While we watched them, we learned a lot about the belief system of the Davidians," Perry said. "One of the things that all of these kids had learned to do, even the really young kids, was march and handle a gun."
Former Davidian Joann Vaega, 6 years old at the time, was one of the children released early in the standoff. Once she was on the outside, she said, "Everything was different."
"Trying to understand what it's like to take a bath just seemed very scary to me, flushing toilets scared the bejeebers out of me," Vaega continued. "I had no idea what the heck a basketball was."
Former Davidian David Bunds said Koresh wouldn't let his own children go. Believing himself to be the next messiah, Bunds said Koresh saw his children as "special" because they were "born from the message of God."
On April 19, 1993, federal agents decided to make their move. An FBI agent got on the loudspeaker and told Koresh that this was his final chance to surrender. Then, agents began moving towards the compound with modified tanks and firing tear gas.
"The tank came into the front doors, the two double doors... and they just blew everything back," said Thibodeau, who was inside the compound when the agents stormed in. "It was amazing to see a tank come through your living room."
"There were no gas masks for the children so the parents were soaking towels in buckets of water," said Clive Doyle, another Davidian inside during the siege.
Around 12 p.m., four hours into the tear gas operation, a set of fires broke out within the compound. The fire moved quickly engulfing everything in flames.
Davidians can be heard discussing "the lighting of fires" in bugging devices that the FBI had smuggled inside. An overhead aerial infrared camera shows the fire starting simultaneously in three different locations and a Congressional investigation concluded that Koresh and his followers set the fire themselves.
Despite this evidence, speculation over whether federal agents or the Davidians are responsible for the fire continues. Conspiracy theorists are likely spurred on by government missteps during the raid and the subsequent standoff. Thibodeau and others are still adamant that the fault remains with the FBI.
Bunds believed Koresh had started it on purpose to be "in control" of the situation, but Doyle said he didn't see where the fire was started.
"[I] didn't see where it started or who lit it or didn't light it, whether it was an accident, whether it was deliberate," Dolye said. "David had told the mothers to take all the children into the vault, which was the bottom part of the four-story tower."
Davidians had a bunker that they practiced going into, Vaega said, "in the event that the end of the world were coming."
The remains of 18 children and nine women were later found inside this bunker vault. The majority had died of smoke inhalation.
Those inside say the tanks destroyed the interior staircases, trapping many on the second floor. David Thibodeau says he barely escaped.
"The wall started to catch fire and I could feel the heat," Thibodeau said. "It singed the side of my face... I could hear my hair crackle."
As the fire closed in, both Doyle and Thibodeau said they ran to escape the swirling inferno, jumping through a hole ripped open in the building by one of the government tanks.
"I could hear some of the ones that were further back into the building behind me screaming," Doyle said. "I thought, 'Nobody's getting out of there now.'"
In the end, about 80 people, including more than 20 children, died in the fire. Only nine people survived.
After the fire was put out, federal agents combed the scene and found Koresh's body. Bob Ricks, one of the FBI's Assistant Special Agents in Charge, told ABC News that "Koresh had a bullet wound right in his forehead which came from a rifle."
But for many of the agents, when it comes to the tragedy now known as the Waco massacre, it's the children's deaths they think about most.
"These children, they're innocent, they don't know," Robert Elder said. "These children being killed, that didn't have to happen. David Koresh is the cause of why it all happened."